1. Technical Field
The present invention relates to semiconductor devices and processing, and more particularly to devices and methods for forming a buried plate for deep trench capacitors that permits a shallow well to be formed in a substrate.
2. Description of the Related Art
Deep trench capacitors include two electrodes. One electrode is formed by filling a deep trench with a conductor. The other electrode is formed in a region adjacent to the deep trench and is known as a buried plate. The buried plate and the conductor are separated by a dielectric layer. The deep trench buried plate requires a low resistance path to ground. This is achieved through the doping of the buried plate which connects the buried plate of each cell to ground.
Since the doped region around the deep trench (buried plate) takes up precious device area, the formation of wells and other structures in areas around the buried plate is not available. In addition, counter doping a heavily doped substrate is challenging especially when forming wells for other devices.